Shaft balanced via magnetically distributed weighted particles and related machine and method

ABSTRACT

The present teachings provide for a method of balancing a shaft. The method can include depositing a mixture of a liquid and ferromagnetic particles on a first surface of a shaft. The first surface can be disposed about a longitudinal axis of the shaft. The method can include rotating the shaft about the longitudinal axis at a first angular velocity. The method can include applying a first magnetic field distribution to the rotating shaft to move the ferromagnetic particles into a desired weight distribution about the first surface. The method can include solidifying the liquid to fix the ferromagnetic particles to the first surface in the desired weight distribution.

FIELD

The present disclosure relates to a shaft balanced via magneticallydistributed weighted particles and a related machine and method forbalancing a hollow shaft with magnetically distributed weightedparticles.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

In the manufacture of modern vehicle propeller shaft assemblies, it iscommon practice to include a balancing process to identify andcounteract an unbalanced condition of a propeller shaft assembly, whichtypically includes a shaft, such as a hollow shaft capped on both ends,such as with cardan joints for example. A typical balancing process thatutilizes a balancing machine is often included as one of the finaloperations in the overall manufacturing process of the propeller shaftassembly. The balancing machine will typically rotate the propellershaft assembly at a predetermined speed and sense vibrations that can becaused by an unbalanced propeller shaft structure. The balancing machinethen identifies where one or more balancing weights, typically solidmasses, may need to be positioned on the propeller shaft assembly tocounteract the vibrations caused by the unbalanced structure. Once thedesired weight positions are identified, the typical balancing machinemust stop rotation of the propeller shaft so that these weights can beaffixed to discrete locations on an exterior surface of the propellershaft, such as by adhesives or welding.

In some instances, the propeller shaft can become damaged during theprocess of physically affixing the solid weights to the exterior surface(e.g., due to high weld temperatures) and the propeller shaft assemblythen has to be re-worked or scrapped. In other instances, the weightscan be incorrectly positioned or affixed, causing the propeller shaftassembly to also be re-worked or scrapped. Furthermore, in someapplications it is desirable that the exterior surface of the propellershaft be coated or painted. In such applications, the typical balancingprocess requires that the weights be attached to the propeller shaftbefore such a coating or paint is applied in order to ensure properattachment to the propeller shaft. However, imperfections in theapplication of the coating or paint can subsequently cause imbalances inthe propeller shaft assembly, which can require the propeller shaftassembly to be re-worked or scrapped. Furthermore, since the hollowshaft is typically capped on both ends during the balancing process, theweights typically cannot be positioned and affixed to the interior ofthe hollow shaft.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present teachings provide for a method of balancing a shaft. Themethod can include depositing a mixture of a liquid and ferromagneticparticles on a first surface of a shaft. The first surface can bedisposed about a longitudinal axis of the shaft. The method can includerotating the shaft about the longitudinal axis at a first angularvelocity. The method can include applying a first magnetic fielddistribution to the rotating shaft to move the ferromagnetic particlesinto a desired weight distribution about the first surface. The methodcan include solidifying the liquid to fix the ferromagnetic particles tothe first surface in the desired weight distribution.

The present teachings also provide for a method of balancing a shaft.The method can include suspending ferromagnetic particles in a liquid toform a mixture. The method can include depositing the mixture on aninterior surface of a hollow shaft. The interior surface can be disposedabout a longitudinal axis of the hollow shaft. The method can includerotating the hollow shaft about the longitudinal axis at a first angularvelocity. The method can include detecting imbalances in the hollowshaft. The method can include activating an electromagnet disposed aboutan exterior of the hollow shaft to apply a first magnetic fielddistribution to the hollow shaft to attract the ferromagnetic particlesto at least one desired location about the interior surface. The methodcan include rotating the first magnetic field distribution about therotational axis at the first angular velocity while the hollow shaftrotates at the first angular velocity. The method can includesolidifying the liquid to fix the ferromagnetic particles to theinterior surface in the desired locations.

The present teachings also provide for a shaft balancing device forbalancing a shaft. The shaft balancing device can include a first endunit, a second end unit, a motor, an electromagnet and a control module.The first end unit can include a first support rotatable about an axisand adapted to be releasably attached to one end of a shaft. The secondend unit can include a second support rotatable about the axis andadapted to be releasably attached to an opposite end of the shaft. Themotor can be drivingly coupled to the first support to rotate the firstsupport about the axis. The electromagnet can be disposed about the axisand axially between the first and second end units. The electromagnetcan be configured to produce a magnetic field. The control module can bein communication with the electromagnet and configured to rotate themagnetic field about the axis.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a schematic view of an example of a machine for balancing ashaft, constructed in accordance with the present teachings;

FIG. 2 is a perspective view of a portion of the machine and shaft ofFIG. 1;

FIG. 3 is another perspective view of the portion of the machine andshaft of FIG. 2;

FIG. 4 is a schematic sectional view of the portion of the machine andshaft of FIG. 2, as viewed down a central axis of the shaft,illustrating the shaft and machine in a first operational state;

FIG. 5 is a schematic sectional view similar to FIG. 4, illustrating theshaft and machine in a second operational state;

FIG. 6 is a schematic sectional view similar to FIG. 4, illustrating theshaft and machine in a third operational state;

FIG. 7 is a schematic sectional view similar to FIG. 4, illustrating theshaft and machine in a fourth operational state; and

FIG. 8 is a flow chart of a method of balancing a shaft in accordancewith the present teachings.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

With reference to FIG. 1 of the drawings, an example of a shaftbalancing machine 10 is illustrated supporting a shaft 14 for balancing.In the example provided, the shaft 14 is a hollow shaft and a componentof a propshaft assembly 18, though other configurations can be used. Thehollow shaft 14 can extend longitudinally along a central rotationalaxis 22 between opposite axial ends. In the example provided, thepropshaft assembly 18 includes the hollow shaft 14, a first end bracket26 at the first axial end, and a second end bracket 30 at the secondaxial end. The first end bracket 26 and second end bracket 30 can capoff the axial ends of the hollow shaft 14 and can seal the interior ofthe hollow shaft 14 to prevent liquid and/or particles from entering orexiting the hollow shaft 14. In the example provided, the hollow shaft14, the first end bracket 26, and the second end bracket 30 are formedof aluminum and the first and second end brackets 26, 30 are welded tothe axial ends of the hollow shaft 14, though other configurations ormaterials can be used.

The shaft balancing machine 10 can include a first end unit 34, a secondend unit 38, at least one weight positioning unit 42, a control module46, and at least one sensor 50. A power source 54 can provide electricalpower to the shaft balancing machine 10. The first end unit 34 andsecond end unit 38 can be configured to support the opposite axial endsof the hollow shaft 14 for rotation about the axis 22. In the exampleprovided, the first end unit 34 can include a first support 58 that canbe releasably coupled to the first end bracket 26 for common rotationabout the axis 22. In the example provided, the first end bracket 26 andfirst support 58 are mating parts of a universal joint, though otherconfigurations can be used. In the example provided, the second end unit38 can include a second support 62 that can be releasably coupled to thesecond end bracket 30 for common rotation about the axis 22. In theexample provided, the second end bracket 30 and second support 62 aremating parts of a universal joint, though other configurations can beused.

In an alternative configuration, not specifically shown, one or both ofthe first support 58 or the second support 62 can be a chuck and thecorresponding axial end of the hollow shaft 14 can include a memberother than a universal joint that caps that axial end, or that axial endcan remain uncapped (i.e., can remain open). In such a configuration,the chuck (not shown) can fixedly, but releasably, grip the respectiveaxial end of the hollow shaft 14 for common rotation about the axis 22.

In the example provided, the first end unit 34 includes a motor 66drivingly coupled to the first support 58 to rotate the first support 58about the axis 22. In an alternative construction, not specificallyshown, the second end unit 38 includes the motor 66. In anotherconstruction, not specifically shown, both the first end unit 34 and thesecond end unit 38 include motors similar to the motor 66 and areconfigured to rotate the first and second supports 58, 62 at the samerate.

The sensor 50 can be any suitable type of sensor configured to detectimbalances in a rotating shaft. In the example provided, the sensor 50is an accelerometer, though other types of sensors can be used. In theexample provided there are two sensors 50, with one of the sensors 50being mounted to the first end unit 34 and the other one of the sensors50 being mounted to the second end unit 38, though other configurationscan be used. The sensors 50 can be of similar types, or of differenttypes from one another.

The weight positioning unit 42 can be disposed axially between the firstend unit 34 and the second end unit 38. The weight positioning unit 42can include an electromagnet 70 and a curing device 74 that can both bedisposed about the axis 22. The hollow shaft 14 can extend through theweight positioning unit 42 and through the electromagnet 70 and thecuring device 74 such that the electromagnet 70 and the curing device 74can be disposed about the hollow shaft 14. In the example provided,there are two weight positioning units 42, with one of the weightpositioning units 42 located axially proximate to the first end unit 34,and the other one of the weight positioning units 42 located axiallyproximate to the second end unit 38, though other configurations can beused. The two weight balancing units 42 can be similar, while beingindependently controlled by the control module 46. Thus, in the exampleprovided, the balancing machine 10 can be configured for two-axisbalancing, to balance each end of the hollow shaft 14 independently ofeach other, though other configurations can be used. The two weightbalancing units 42 may also be operated simultaneously such that bothends of the hollow shaft 14 may be balanced simultaneously, though otherconfigurations can be used. The electromagnet 70 and the curing device74 of one of the weight positioning units 42 are described in greaterdetail below. The electromagnet 70 and the curing device 74 of the otherone of the weight positioning units can be constructed and operatedsimilarly.

With additional reference to FIGS. 2 and 3, a portion 210 of the hollowshaft 14 that is disposed within the weight positioning unit 42 (FIG. 1)is illustrated with an example electromagnet 70 and curing device 74.The hollow shaft 14 can have a cylindrical exterior surface 214 and acylindrical interior surface 218 that can be coaxially disposed aboutthe axis 22 and can extend axially between the axial ends of the hollowshaft 14. The interior surface 218 can be radially inward of theexterior surface 214. In the example provided, the hollow shaft 14 canhave a generally constant thickness (i.e., distance between the exteriorand interior surfaces 214, 218) along the length of the portion 210,though other configurations can be used.

The electromagnet 70 can include a plurality of coil units 222 disposedcircumferentially about the axis 22. In the example provided, the coilunits 222 are equally spaced about the axis 22 and disposed radiallyoutward of the exterior surface 214 of the hollow shaft 14. In theexample provided, the electromagnet 70 includes twelve coil units 222(indicated as 222 a-l), though greater or fewer coil units 222 can beused. Each coil unit 222 can have a plurality of coils 226 formed ofconductive wire that can be coiled about a respective spool 230. Eachspool 230 can be fixedly supported about the hollow shaft 14 by anannular support ring 234 disposed about the axis 22. The spools 230 canhold the coils 226 radially outward of the exterior surface 214 of thehollow shaft 14. The coils 226 can be arranged on their respectivespools 230 such that when the coil unit 222 is activated and electricalcurrent flows through the respective coils 226, a magnetic field (notshown) is generated. The electromagnet 70 can be spaced apart from thehollow shaft 14 and the magnetic field (not shown) can be a strengthsuch that the magnetic field can penetrate through the hollow shaft 14to reach the interior surface 218. The hollow shaft 14 can rotate aboutthe axis 22 relative to the electromagnet 70.

The coil units 222 can be in electrical communication with the controlmodule 46. The control module 46 can be in electric communication withthe power source 54. The control module 46 can be located within theweight positioning unit 42, or can be located external to the weightpositioning unit 42. The power source 54 can be any suitable source ofelectrical power, such as an electrical storage medium (e.g., battery),or an external electrical supply (e.g., AC or DC power lines). Thecontrol module 46 can be configured to control the supply of electricalpower to the electromagnet 70. The control module 46 can also be inelectrical communication with the motor 66 (FIG. 1) to supply power tothe motor 66 (FIG. 1) to control operation of the motor 66 (FIG. 1). Thecontrol module 46 can also be in electrical communication with thesensor 50 (FIG. 1) to receive input from the sensor 50 (FIG. 1)indicative of a magnitude and location of imbalances within the hollowshaft 14 as the hollow shaft 14 rotates about the axis 22, as describedbelow.

The control module 46 can be configured to control power to individualones of the coil units 222 separately from other ones of the coil units222. Thus, the control module 46 can control the locations and/orstrengths of the magnetic fields generated about the hollow shaft 14 andcan selectively change the locations and/or strengths of the magneticfields.

The curing device 74 can be configured to cure (i.e., solidify) a liquidmaterial 238 that can be located within the interior of the hollow shaft14 axially aligned with the electromagnet 70. A plurality offerromagnetic particles 242 can be suspended in the liquid material 238.The liquid material 238 may be a viscous liquid. In the exampleprovided, the liquid material 238 is a heat-curable resin and the curingdevice 74 includes an inductive heating coil 246, though otherconfigurations can be used. For example, the curing device 74 can be aresistance heating element and the control module 46 can selectivelyprovide electrical current to the curing device 74 to heat theresistance heating element to heat the hollow shaft 14. In the exampleprovided, the ferromagnetic particles 242 are iron granules, thoughother configurations can be used. The liquid material 238 andferromagnetic particles 242 are described in greater detail below.

The inductive heating coil 246 can circumscribe a portion 210 of thehollow shaft 14 adjacent to the electromagnet 70, such that theinductive heating coil 246 can heat the portion 210 of the hollow shaft14 at least in an axial location where the liquid material 238 ispresent. The control module 46 can be in electrical communication withthe curing device 74 to operate the inductive heating coil 246. In theexample provided, the control module 46 selectively provides highfrequency AC electrical current to the inductive heating coil 246 toproduce a rapidly alternating magnetic field that can heat the portion210 of the hollow shaft 14. The strength, frequency, and location of themagnetic field produced by the inductive heating coil 246 can beconfigured so as to not interfere with the operation of theelectromagnet 70 and the interactions between the magnetic fields of theelectromagnet 70 and the ferromagnetic particles 242, described below.

With continued reference to FIGS. 1-3 and additional reference to FIGS.4-8, operation of the shaft balancing machine 10 is described. FIG. 8illustrates a method 810 of operating the shaft balancing machine 10 inflow-chart format. FIGS. 4-7 schematically illustrate operation of theelectromagnet 70 and rotation of the hollow shaft 14 during theoperation of the shaft balancing machine 10. The distribution of theferromagnetic particles 242 in the liquid material 238 is schematicallyillustrated in FIGS. 4-7 by layer 408. The radial thicknesses of thelayer 408, which includes the liquid material 238 and the ferromagneticparticles 242, is schematically exaggerated in FIGS. 4-7 to betterillustrate the operation of the shaft balancing machine 10.

At step 814, the liquid material 238 can be mixed with the ferromagneticparticles 242 and the mixture can be deposited along the interiorsurface 218 of the hollow shaft 14. The hollow shaft 14 can be mountedto the first and second end units 34, 38 either before or after themixture is deposited within the hollow shaft 14. In the exampleprovided, the end brackets 26, 30 can be affixed to the hollow shaft 14after the mixture is deposited, such that the mixture can be sealedwithin the propshaft assembly 18, and the propshaft assembly 18 can thenbe mounted to the first and second end units 34, 38.

After the mixture is within the hollow shaft 14 and the hollow shaft 14is mounted to the shaft balancing machine 10, the method 810 can proceedto step 818. At step 818, a homogeneous suspension of the ferromagneticparticles 242 within the liquid material 238 can be created. To createthe homogeneous suspension, the motor 66 can be operated to rotate thehollow shaft 14 about the axis 22. At step 818, the electromagnet 70 canbe activated to produce a magnetic field (not shown) of a first fielddistribution. The first field distribution can be uniform around thecircumference of the hollow shaft 14 and stationary relative to the axis22. For example, the control module 46 can activate all of the coilunits 222, or every other one of the coil units 222, or anotherdistribution of the coil units 222 that produces an overall magneticfield that is evenly distributed circumferentially about the hollowshaft 14. In the example illustrated in FIG. 4, the activated coil units222 are illustrated with shading to schematically indicate theiractivated state. In the example provided, every other coil unit 222 isactivated to produce a circumferentially uniform magnetic field.

The control module 46 can keep the magnetic field stationary relative tothe axis 22 while the hollow shaft 14 rotates about the axis 22. In theexample illustrated in FIG. 4, the rotation of the hollow shaft 14 isschematically indicated by arrow 410 and has an angular velocity ofω1>0, while the rotation of the magnetic field is indicated by arrow 414and has an angular velocity of ω2=0. In the example provided, ω1 is 600revolutions per minute, though other speeds can be used. This rotationof the hollow shaft 14 through the stationary magnetic field can stirthe ferromagnetic particles 242 in the liquid material 238 to create ahomogeneous suspension of the ferromagnetic particles 242. Thus, thelayer 408 is schematically illustrated as having a uniform thicknessabout the interior surface 218. The rotation of the hollow shaft 14 canalso distribute the liquid material 238 within the hollow shaft 14, suchthat the liquid material 238 has a uniform radial thickness about theinner circumference of the hollow shaft 14. Once the homogeneoussuspension is created, the method 810 can proceed to step 822 withoutinterruption of the rotation of the hollow shaft 14.

At step 822, the hollow shaft 14 can continue to rotate at an angularvelocity ω1>0 and the control module 46 can change the magnetic field toa second field distribution. The second field distribution can be suchthat the magnetic field can be rotated at an angular velocity equal tothat of the hollow shaft 14 (e.g., ω2=ω1>0). In other words, themagnetic field can be rotated about the axis 22 at the same angularvelocity as the hollow shaft 14. In the example provided, ω1 and ω2 are600 RPM, though other rotational speeds can be used.

In the example provided, the magnetic field is rotated by altering whichones of the coil units 222 are activated. In the example provided, coilunits 222 a, 222 c, 222 e, 222 g, 222 i, and 222 k are initiallyactivated, with the others deactivated, then coil units 222 b, 222 d,222 f, 222 h, 222 j, and 222 l are activated, with the othersdeactivated, and the sequence repeats to rotate the magnetic field.While every other coil unit 222 is shown activated, other distributionsand sequences of activated coil units 222 can be used to rotate themagnetic field, such as coil units 222 a, 222 d, 222 g, and 222 j, then222 b, 222 e, 222 h, 222 k, then 222 c, 222 f, 222 i, 222 l, forexample.

In an alternative configuration, the particular coil units 222 that areactivated can remain constant, while the coil units 222 physicallyrotate about the axis 22 in order to cause the magnetic field to rotateabout the axis 22. In such an alternative construction, the annularsupport ring 234 can rotate about the axis 22 to rotate the coil units222. In this alternative construction, the control module 46 can stillcontrol or change the activation of specific coil units 222 to controlor change the circumferential distribution of the magnetic fields (e.g.,an arc length of the hollow shaft 14 through which the magnetic fieldsare strongest).

Once the magnetic field is rotating at the same angular velocity as thehollow shaft 14, the method 810 can proceed to step 826. At step 826,while the magnetic field and the hollow shaft 14 rotate at the sameangular velocity (e.g., ω2=ω1=600 RPM), the control module 46 canreceive and interpret signals received from the sensor 50 to identify aweight distribution profile. The weight distribution profile canindicate circumferential locations where additional weight is needed tobalance the hollow shaft 14, and how much weight is needed in thoselocations to achieve a desired level of balance. Once the weightdistribution profile is determined, the method 810 can proceed to step830.

At step 830, the angular velocity of the hollow shaft 14 can remainequal to the angular velocity of the magnetic field (e.g., ω2=ω1=600RPM). The control module 46 can adjust the circumferential distributionof the activated coil units 222 based on the weight distribution profileto produce a third field distribution. In other words, the controlmodule 46 can adjust the strength and/or location of the activated coilunits 222 to concentrate the magnetic field in areas where additionalweight is needed to balance the rotating hollow shaft 14.

In the example provided, FIGS. 5-7 illustrate the control module 46incrementally changing the circumferential locations of the activatedcoil units 222. For example, FIG. 5 illustrates coil units 222 c, 222 e,222 g, 2221, and 222 k activated such that a region of activated coilunits 222 is provided throughout the arc length 510 between dashed lines514, 518. The activated region of the arc length 510 rotates such thatthe magnetic field continues to rotate at an angular velocity equal tothe angular velocity of the hollow shaft 14 (e.g., ω2=ω1=600 RPM). Thus,the suspended ferromagnetic particles 242 can be magnetically attractedto the region of the arc length 510 to provide additional weight withinthe arc length 510. This concentration of the ferromagnetic particles242 is illustrated in FIGS. 5-7 by the schematic thickening of the layer408, though it is appreciated that the actual thickness of the liquidmaterial 238 can remain uniform while the ferromagnetic particles 242can become more concentrated in the areas of the layer 408 that areschematically illustrated as thicker.

The control module 46 can continue to receive and analyze input from thesensor 50 (FIG. 1) to update the weight distribution profile and modifythe arc length 510 until the desired balance is achieved. In the exampleprovided, FIGS. 6 and 7 illustrate sequential arc lengths 510′ and 510″of coil unit 222 activation to achieve a final weight distributionprofile schematically shown in FIG. 6. The control module 46 can rotatethe hollow shaft 14 and the arc length 510 for a predetermined amount oftime at each arc length 510, 510′, 510″, or until a desired balance isdetected, then proceed to the next arc length 510, 510′, 510″.

While a single arc length 510,510′,510″ is illustrated, the controlmodule 46 can activate and rotate activation of the coil units 222 toproduce additional activated arc lengths (not shown) that can becircumferentially spaced apart from the arc length 510, 510′, or 510″ ifmultiple, circumferentially separated locations need additional weightto achieve the desired balance.

After the desired weight distribution is achieved to balance the hollowshaft 14, the method can proceed to step 834. At step 834, the hollowshaft 14 and magnetic field can continue to rotate at equal velocities(e.g., ω2=ω1=600 RPM), while the curing device 74 can cure the liquidmaterial 238 to fix the distribution of the ferromagnetic particles 242relative to the hollow shaft 14.

In one alternative construction of the curing device 74, notspecifically shown, the curing device 74 can be similar to thatillustrated in FIGS. 2-7, except one axial end of the hollow shaft 14can be open and the curing device 74 can be received therein to bedisposed radially inward of the interior surface 218 of the hollow shaft14. The curing device 74 can be an induction heating coil similar to thecuring device 74 described above with reference to FIGS. 2-7, to heatthe hollow shaft 14 from the inside, though other configurations can beused. For example, the liquid material 238 can be configured to be curedby introduction of a curing chemical substance (not shown) and thecuring device 74 can be configured to distribute that curing chemicalsubstance within the hollow shaft 14. In another example, the liquidmaterial 238 can be configured to cure in reaction to exposure to lightof a predetermined wavelength (e.g., UV light) and the curing device 74can be configured to emit light of the predetermined wavelength to curethe liquid material 238.

In another alternative construction, the weight positioning unit 42 doesnot include the curing device 74. In this alternative construction, theliquid material 238 can be configured to cure after a predeterminedamount of time. In operation at step 834, the control module 46 can beconfigured to rotate the hollow shaft 14 and the magnetic field in thefinal weight distribution until that predetermined amount of time passesand the liquid material 238 cures within the hollow shaft 14.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,”“lower,” “above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

In this application, including the definitions below, the term “module”or the term “controller” may be replaced with the term “circuit.” Theterm “module” may refer to, be part of, or include: an ApplicationSpecific Integrated Circuit (ASIC); a digital, analog, or mixedanalog/digital discrete circuit; a digital, analog, or mixedanalog/digital integrated circuit; a combinational logic circuit; afield programmable gate array (FPGA); a processor circuit (shared,dedicated, or group) that executes code; a memory circuit (shared,dedicated, or group) that stores code executed by the processor circuit;other suitable hardware components that provide the describedfunctionality; or a combination of some or all of the above, such as ina system-on-chip.

The module may include one or more interface circuits. In some examples,the interface circuits may include wired or wireless interfaces that areconnected to a local area network (LAN), the Internet, a wide areanetwork (WAN), or combinations thereof. The functionality of any givenmodule of the present disclosure may be distributed among multiplemodules that are connected via interface circuits. For example, multiplemodules may allow load balancing. In a further example, a server (alsoknown as remote, or cloud) module may accomplish some functionality onbehalf of a client module.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes, datastructures, and/or objects. The term shared processor circuitencompasses a single processor circuit that executes some or all codefrom multiple modules. The term group processor circuit encompasses aprocessor circuit that, in combination with additional processorcircuits, executes some or all code from one or more modules. Referencesto multiple processor circuits encompass multiple processor circuits ondiscrete dies, multiple processor circuits on a single die, multiplecores of a single processor circuit, multiple threads of a singleprocessor circuit, or a combination of the above. The term shared memorycircuit encompasses a single memory circuit that stores some or all codefrom multiple modules. The term group memory circuit encompasses amemory circuit that, in combination with additional memories, storessome or all code from one or more modules.

The term memory circuit is a subset of the term computer-readablemedium. The term computer-readable medium, as used herein, does notencompass transitory electrical or electromagnetic signals propagatingthrough a medium (such as on a carrier wave); the term computer-readablemedium may therefore be considered tangible and non-transitory.Non-limiting examples of a non-transitory, tangible computer-readablemedium are nonvolatile memory circuits (such as a flash memory circuit,an erasable programmable read-only memory circuit, or a mask read-onlymemory circuit), volatile memory circuits (such as a static randomaccess memory circuit or a dynamic random access memory circuit),magnetic storage media (such as an analog or digital magnetic tape or ahard disk drive), and optical storage media (such as a CD, a DVD, or aBlu-ray Disc).

The apparatuses and methods described in this application may bepartially or fully implemented by a special purpose computer created byconfiguring a general purpose computer to execute one or more particularfunctions embodied in computer programs. The functional blocks,flowchart components, and other elements described above serve assoftware specifications, which can be translated into the computerprograms by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that arestored on at least one non-transitory, tangible computer-readablemedium. The computer programs may also include or rely on stored data.The computer programs may encompass a basic input/output system (BIOS)that interacts with hardware of the special purpose computer, devicedrivers that interact with particular devices of the special purposecomputer, one or more operating systems, user applications, backgroundservices, background applications, etc.

The computer programs may include: (i) descriptive text to be parsed,such as HTML (hypertext markup language) or XML (extensible markuplanguage), (ii) assembly code, (iii) object code generated from sourcecode by a compiler, (iv) source code for execution by an interpreter,(v) source code for compilation and execution by a just-in-timecompiler, etc. As examples only, source code may be written using syntaxfrom languages including C, C++, C#, Objective C, Haskell, Go, SQL, R,Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5,Ada, ASP (active server pages), PHP, Scala, Eiffel, Smalltalk, Erlang,Ruby, Flash®, Visual Basic®, Lua, and Python®.

None of the elements recited in the claims are intended to be ameans-plus-function element within the meaning of 35 U.S.C. § 112(f)unless an element is expressly recited using the phrase “means for,” orin the case of a method claim using the phrases “operation for” or “stepfor.”

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments

What is claimed is:
 1. A method of balancing a shaft, the methodcomprising: depositing a mixture of a liquid and ferromagnetic particleson a first surface of a shaft, the first surface being deposited about alongitudinal axis of the shaft; rotating the shaft about thelongitudinal axis at a first angular velocity; applying a first magneticfield distribution to the rotating shaft to move the ferromagneticparticles into a desired weight distribution about the first surface;and solidifying the liquid to permanently fix the ferromagneticparticles to the first surface in the desired weight distribution. 2.The method of claim 1, further comprising: before applying the firstmagnetic field distribution, creating a homogeneous suspension of theferromagnetic particles in the liquid about the first surface.
 3. Themethod of claim 2, wherein creating the homogeneous suspension of theferromagnetic particles in the liquid about the first surface includesapplying a second magnetic field distribution while rotating the shaftat a second angular velocity.
 4. The method of claim 3, wherein thesecond magnetic field distribution is a non-rotating magnetic fielddisposed evenly about the longitudinal axis.
 5. The method of claim 1,wherein the first magnetic field distribution is a rotating magneticfield that rotates about the longitudinal axis at the first angularvelocity while the shaft rotates about the longitudinal axis at thefirst angular velocity.
 6. The method of claim 1, further comprising:before applying the first magnetic field distribution: applying a secondmagnetic field distribution while the shaft rotates at the first angularvelocity, wherein the second magnetic field distribution is a rotatingmagnetic field disposed evenly about the longitudinal axis and rotatingabout the longitudinal axis at the first angular velocity; whileapplying the second magnetic field distribution and rotating the shaftat the first angular velocity: detecting imbalances in the shaft; anddetermining a desired weight distribution to balance the shaft.
 7. Themethod of claim 1, wherein solidifying the liquid includes heating aportion of the shaft to a predetermined temperature.
 8. The method ofclaim 7, wherein heating the portion of the shaft includes activating aninduction heating coil disposed about the shaft.
 9. The method of claim1, wherein solidifying the liquid includes rotating the shaft and thefirst magnetic field distribution at the first angular velocity for apredetermined amount of time.
 10. The method of claim 1, wherein theshaft is a hollow shaft and the first surface is an interior surface ofthe hollow shaft.
 11. The method of claim 10, further comprising:sealing the liquid within the hollow shaft before applying the firstmagnetic field distribution.
 12. A method of balancing a shaft, themethod comprising: suspending ferromagnetic particles in a liquid toform a mixture; depositing the mixture on an interior surface of ahollow shaft, the interior surface being disposed about a longitudinalaxis of the hollow shaft; rotating the hollow shaft about thelongitudinal axis at a first angular velocity; detecting imbalances inthe hollow shaft; activating an electromagnet disposed about an exteriorof the hollow shaft to apply a first magnetic field distribution to thehollow shaft to attract the ferromagnetic particles to at least onedesired location about the interior surface; rotating the first magneticfield distribution about the rotational axis at the first angularvelocity while the hollow shaft rotates at the first angular velocity;and solidifying the liquid to permanently fix the ferromagneticparticles to the interior surface in the desired locations.
 13. Themethod of claim 12, further comprising: before detecting imbalances inthe hollow shaft, activating the electromagnet to apply a secondmagnetic field distribution while rotating the shaft at a second angularvelocity, wherein the second magnetic field distribution is anon-rotating magnetic field disposed evenly about the longitudinal axis.14. The method of claim 12, further comprising: before applying thefirst magnetic field distribution, applying a second magnetic fielddistribution while the shaft rotates at the first angular velocity,wherein the second magnetic field distribution is a rotating magneticfield disposed evenly about the longitudinal axis and rotating about thelongitudinal axis at the first angular velocity; while applying thesecond magnetic field distribution and rotating the hollow shaft at thefirst angular velocity, detecting imbalances in the hollow shaft; anddetermining a desired weight distribution to balance the hollow shaft.15. The method of claim 12, wherein solidifying the liquid includesheating a portion of the hollow shaft to a predetermined temperature.16. The method of claim 12, wherein solidifying the liquid includesrotating the hollow shaft and the first magnetic field distribution atthe first angular velocity for a predetermined amount of time.
 17. Themethod of claim 12, further comprising: sealing the liquid within thehollow shaft before activating the electromagnet to apply the firstmagnetic field distribution.